Re: [PATCH] r8169: Reinstate ALDPS and ASPM support

Bjorn Helgaas
2018-06-05T19:11:47Z

[+cc linux-pci]

On Tue, Jun 05, 2018 at 12:28:05PM -0500, Bjorn Helgaas wrote:
> On Tue, Jun 05, 2018 at 06:34:09AM +0000, Ryankao wrote:
> > Add realtek folk Hau
> >
> > -----Original Message-----
> > From: Kai Heng Feng [mailto:kai.heng.feng@canonical.com]
> > Sent: Tuesday, June 05, 2018 1:02 PM
> > To: jrg.otte@gmail.com
> > Cc: David Miller <davem@davemloft.net>; Hayes Wang <hayeswang@realtek.com>; hkallweit1@gmail.com; romieu@fr.zoreil.com; Linux Netdev List <netdev@vger.kernel.org>; Linux Kernel Mailing List <linux-kernel@vger.kernel.org>; Ryankao <ryankao@realtek.com>
> > Subject: Re: [PATCH] r8169: Reinstate ALDPS and ASPM support
> >
> > Hi Jörg Otte,
> >
> > Can you give this patch a try?
> >
> > Since you are the only one that reported ALDPS/ASPM regression,
> >
> > And I think this patch should solve the issue you had [1].
> >
> > Hopefully we don't need to go down the rabbit hole of blacklist/whitelist...
> >
> > Kai-Heng
> >
> > [1] https://lkml.org/lkml/2013/1/5/36
>
> I have no idea what ALDPS is. It's not mentioned in the PCIe spec, so
> presumably it's some Realtek-specific thing. ASPM is a generic PCIe
> thing. Changes to these two things should be in separate patches so
> they don't get tangled up.
>
> > > On Jun 5, 2018, at 12:58 PM, Kai-Heng Feng
> > > <kai.heng.feng@canonical.com>
> > > wrote:
> > >
> > > This patch reinstate ALDPS and ASPM support on r8169.
> > >
> > > On some Intel platforms, ASPM support on r8169 is the key factor to
> > > let Package C-State achieve PC8. Without ASPM support, the deepest
> > > Package C-State can hit is PC3. PC8 can save additional ~3W in
> > > comparison with PC3.
> > >
> > > This patch is from Realtek.
> > >
> > > Fixes: e0c075577965 ("r8169: enable ALDPS for power saving")
> > > Fixes: d64ec841517a ("r8169: enable internal ASPM and clock request
> > > settings")
>
> > > +3507,15 @@ static void rtl8168e_1_hw_phy_config(struct
> > > rtl8169_private *tp)
> > > rtl_writephy(tp, 0x0d, 0x4007);
> > > rtl_writephy(tp, 0x0e, 0x0000);
> > > rtl_writephy(tp, 0x0d, 0x0000);
> > > +
> > > + /* Check ALDPS bit, disable it if enabled */
> > > + rtl_writephy(tp, 0x1f, 0x0000);
> > > + if (enable_aldps)
> > > + rtl_w0w1_phy(tp, 0x15, 0x1000, 0x0000);
> > > + else if (rtl_readphy(tp, 0x15) & 0x1000)
> > > + rtl_w0w1_phy(tp, 0x15, 0x0000, 0x1000);
>
> There's a lot of repetition of this code with minor variations. You
> could probably factor it out and make it more concise and more
> readable.
>
> > > +static void rtl8169_check_link_status(struct net_device *dev,
> > > + struct rtl8169_private *tp) {
> > > + struct device *d = tp_to_dev(tp);
> > > +
> > > + if (tp->link_ok(tp)) {
> > > + rtl_link_chg_patch(tp);
> > > + /* This is to cancel a scheduled suspend if there's one. */
> > > + if (pm_request_resume(d))
> > > + _rtl_reset_work(tp);
> > > + netif_carrier_on(dev);
> > > + if (net_ratelimit())
> > > + netif_info(tp, ifup, dev, "link up\n");
> > > + } else {
> > > + netif_carrier_off(dev);
> > > + netif_info(tp, ifdown, dev, "link down\n");
> > > + pm_runtime_idle(d);
> > > + }
> > > +}
>
> This function apparently just got moved around without changing
> anything. That's fine, but the move should be in a separate patch to
> make the real changes easier to review.
>
> > > @@ -7649,8 +7757,12 @@ static int rtl_init_one(struct pci_dev *pdev,
> > > const struct pci_device_id *ent)
> > >
> > > /* disable ASPM completely as that cause random device stop working
> > > * problems as well as full system hangs for some PCIe devices users */
> > > - pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S | PCIE_LINK_STATE_L1 |
> > > - PCIE_LINK_STATE_CLKPM);
> > > + if (!enable_aspm) {
> > > + pci_disable_link_state(pdev, PCIE_LINK_STATE_L0S |
> > > + PCIE_LINK_STATE_L1 |
> > > + PCIE_LINK_STATE_CLKPM);
> > > + netif_info(tp, probe, dev, "ASPM disabled\n");
> > > + }
>
> ASPM is a generic PCIe feature that should be configured by the PCI
> core without any help from the device driver.
>
> If code in the driver is needed, that means either the PCI core is
> doing it wrong and we should fix it there, or the device is broken and
> the driver is working around the erratum.
>
> If this is an erratum, you should include details about exactly what's
> broken and (ideally) a URL to the published erratum. Otherwise this
> is just unmaintainable black magic and likely to be broken by future
> ASPM changes in the PCI core.
>
> ASPM configuration is done by the PCI core before drivers are bound to
> the device. If you need device-specific workarounds, they should
> probably be in quirks so they're done before the core does that ASPM
> configuration.
>
> > > /* enable device (incl. PCI PM wakeup and hotplug setup) */
> > > rc = pcim_enable_device(pdev);
> > > --
> > > 2.17.0
> >
> > ------Please consider the environment before printing this e-mail.